.TH atanh 3 "" "" ""
.SH SYNOPSIS
atanh, atanhf \- inverse hyperbolic tangent
.SH ANSI_SYNOPSIS
#include <math.h>
.br
double atanh(double 
.IR x );
.br
float atanhf(float 
.IR x );
.br
.SH TRAD_SYNOPSIS
#include <math.h>
.br
double atanh(
.IR x )
.br
double 
.IR x ;
.br

float atanhf(
.IR x )
.br
float 
.IR x ;
.br
.SH DESCRIPTION
.BR atanh 
calculates the inverse hyperbolic tangent of 
.IR x .

.BR atanhf 
is identical, other than taking and returning
.BR float 
values.
.SH RETURNS
.BR atanh 
and 
.BR atanhf 
return the calculated value.

If
@ifinfo
|
.IR x |
@end ifinfo
@tex
$|x|$
@end tex
is greater than 1, the global 
.BR errno 
is set to 
.BR EDOM 
and
the result is a NaN. A 
.BR DOMAIN error 
is reported.

If
@ifinfo
|
.IR x |
@end ifinfo
@tex
$|x|$
@end tex
is 1, the global 
.BR errno 
is set to 
.BR EDOM ;
and the result is
infinity with the same sign as 
.BR x .
A 
.BR SING error 
is reported.

You can modify the error handling for these routines using
.BR matherr .
.SH PORTABILITY
Neither 
.BR atanh 
nor 
.BR atanhf 
are ANSI C.
.SH QUICKREF
atanh - pure
atanhf - pure
.SH SOURCE
src/newlib/libm/mathfp/e_atanh.c
